"Hommage" is the word that Zadie Smith uses in her acknowledgements for her novel's relationship with EM Forster's fiction. It is a relationship that she wants us to notice. Before it became pejorative in the 19th century, there was a useful literary term for the special kind of respect paid by her On Beauty to his Howards End: "imitation". An imitation was a rewriting of an original, whose outline you were allowed to keep glimpsing through the new creation.

Every reviewer noticed that On Beauty opens with the opening words of Howards End ("One may as well begin with ..."). It is a beginning that draws attention to its arbitrariness, and to the prominence of the author in finding some shape in the human confusion that follows. Howards End concerns the entanglement of two families - the Schlegels and the Wilcoxes - who represent conflicting values. So too On Beauty, where the Belseys and the Kippses seem comically doomed by Smith's very imitation of Forster to enact a comparable set of conflicts: liberal versus conservative, modern versus traditional. After the embarrassing amorous entanglement of two of their younger members (Helen Schlegel and Paul Wilcox, Jerome Belsey and Victoria Kipps) they are even fated to find themselves living in the same street.

Plot imitation produces a kind of dramatic irony. Just as the cultured Schlegels meet the culture-hungry clerk Leonard Bast at a Beethoven concert, so the Belseys encounter the rap poet Carl at a performance of Mozart's Requiem. In Forster's story Helen takes Leonard's umbrella; in On Beauty, Zora Belsey leaves with Carl's Discman. Thus acquainted, the Belseys play out a bien-pensant condescension towards the uneducated young man that we have, literally, seen before. "Culture" brings them awkwardly together. Thinking of Smith's title, we might even remember that Leonard comes to the concert to "pursue beauty". Though, being poor, there was "always something that distracted him in the pursuit of beauty".

These are matters of plot and theme, but Smith also goes closely into the texture of Forster's novel. Sometimes parallels are minutely observed. In On Beauty, Kiki Belsey gets a note from Carlene Kipps inviting her to go shopping. Kiki may think this comes out of the blue, but a reader of Forster knows better. In Howards End, Margaret received the same message: "would Miss Schlegel come shopping? Christmas was nearing ..." The invitation comes as an answer to Margaret's unspoken question. "Was Mrs Wilcox one of those unsatisfactory people ... who dangle intimacy and then withdraw it?" With a small adjustment for the likely phrasing, Kiki asks just the same question. "Was Carlene Kipps one of those women who promises friendship but never truly delivers it? A friendship flirt?"

The verbal parallels lead the reader into an episode where imitation is painstaking. Carlene, warmed into intimacy, suddenly invites Kiki to her holiday home, "now - let's go now". Just so, Mrs Wilcox impulsively invites Margaret to Howards End. In both books both women decline, then later regret the apparent rejection of friendship, and rush to put it right. Kiki finds Carlene, as Margaret found Mrs Wilcox, on a railway platform, about to depart. And in both books, the older woman's family suddenly arrive on a train to make the jaunt impossible. There is a poignancy, borrowed from Howards End, about this acceptance and then loss of opportunity. We know from Forster's plot that Carlene will die before Kiki can see her again.

In their momentary impulses Smith's characters are acting out roles that have already been laid down. In both novels, a surprising, tentative female friendship is set against the sharp conflicts that otherwise separate the families. Howard Belsey, being an academic who prides himself on his theoretical sophistication, has no time for the author of Howards End. Visiting his aged father Harold, he spots a copy of A Room With a View. "'Forster,' Howard smiled sadly. 'Can't stand Forster. Enjoying it?'" Harold grimaces with distaste; he cannot be doing with it either. The book belongs to the Christian lady who pops round to see that he is all right. She at least appreciates this elegant guide to human muddle.

· John Mullan is professor of English at University College London. Join him and Zadie Smith for a discussion of On Beauty on July 13 at the Newsroom, 60 Farringdon Road, London EC1. Doors open at 6.30pm and entry costs £7. Booking is essential. Call 020 7886 9281 or email book.club@theguardian.com